The present invention concerns generally saw bars of the type coupled to a small engine which drives a continuous saw chain about the perimeter of an elongate saw bar.
Saw bar weight is very important particularly to those in the logging industry for the reason that the cahin saw must be carried over rough terrain and manipulated into position for and during a cutting operation over a period of several hours constituting a work shift. Accordingly, any weight savings effort is highly desirable as over a period of time such would constitute a substantial reduction in the effort required on the saw operator's part. Attempts have been made to lighten saw bar construction, however, apparently such efforts have not been well received in the industry as saw bar construction has apparently not changed, with regard to weight reduction, for many years.
U.S. Pat. No. 4,393,590 discloses a saw bar of composite construction having outer wall surfaces of reinforced plastic material with an inner core of honeycomb metal. The saw tooth guiding channel is defined by solid metal components. Such saw bar construction would result in a bar of greater thickness than conventional saw bars and hence require a wider kerf for blade passage through the work piece. Additionally, such composite construction is believed to be quite costly requiring several steps during bar fabrication.
U.S. Pat. No. 3,191,646 discloses a chain saw bar of laminated construction wherein the outer laminates are steel and the inner laminate being of some lighter metal such as aluminum, magnesium or a plastic. Elongate inserts of wear resistant metal are required to isolate each tooth from the softer inner laminate. The bar is assembled by means of pins. Such blade construction is obviously very costly and of doubtful durability in view of the severe treatment saw bars are subjected to.
U.S. Pat. Nos. 3,301,282 and 3,250,304 both show saw bars of composite construction having insertable wear strips on which the teeth ride with one of the saw bars being of laminated construction.
None of the above-mentioned saw bar structures are known to be commercially available to the public.